The deal of Boniface will be a good one for AC Milan, because presently AC Milan need a striker who can deliver for them in both Serie A and the Europa League. This will be a very good one, as we all know that Boniface is a powerful and consistent player that adapts to new teams easily. So, it will not be that hard for him to adapt to such situations, and that will be like a replacement for Osimhen in the Serie A games, because Boniface is also good, no doubt on that.
Milan getting Boniface would be a huge deal, but Leverkusen already lost a lot of blood this season, I am not sure if they would be willing to let Boniface go as well. And even if they would be willing to, which I doubt, they would still ask for a lot of money.
An amount that Milan can't afford to pay right now. Remember, Serie A teams are not as rich as premier league teams, Liverpool can pay a ton of money to Leverkusen for their players, but Milan can't so if the offer is 50+ million type of dela, then Milan can't afford that. Best I am guessing is about 30 to 40 million and Boniface worths a lot more for them at the moment, Leverkusen can say no to that amount and they can do better with him on the squad instead of selling him.